Insight on the properties of thermoplastic elastomer-based natural rubber and recycled rubber post-treated with electron beam irradiation

Thermoplastic elastomers are an indispensable group of materials used in various relevant industries. This study aims to enhance the properties of thermoplastic elastomers by blending the same ratio of natural rubber (NR) and recycled rubber (RR) with different ratios of high-density polyethylene (HDPE). Therefore, the study examined the effect of irradiation on the crosslinking of the main chain of thermoplastic elastomer (TPE) based on a 1:1 ratio of natural rubber and recycled rubber. TPE was prepared at different time periods and composition ranges by mixing recycled rubber with natural rubber together with HDPE. Using an internal Haake machine mixer, the mixing process was conducted, and the mix was standardized using a two-roll mixer. All samples were exposed under electron beam irradiation for structural modification. The effect of crosslinking in TPE was determined by analyzing the gel content. The high dose of irradiation resulted in a higher gel content, indicating an increase in crosslinking. The effect of irradiation and HDPE as a filler increased TPE's tensile strength, while higher RR/NR compositions improved elongation properties. The irradiation dose of 50 to 150 kGy exhibited an increase in mechanical properties than the unirradiated composites. The FTIR analysis confirmed the presence of a carbonyl group formed after irradiation through a decomposition-oxidation reaction. The study found that high NR/RR ratios increase elongation and thermal characteristics. The homogenous blending of NR/RR/HDPE was shown from the blending profile, crosslinking density, and morphology. The high amounts of NR/RR ultimately enhance TPE's thermal stability. (paper)